There may be a case where, in a device fixed to a mobile body, items to be operated are restricted depending on whether the mobile body is traveling or stopping, particularly for the sake of safety driving. For example, a car navigation system mounted on a vehicle has not only a navigation function for guiding the vehicle to a destination but also a multi-function such as reproduction of a music file by using various mediums including a CD, a DVD, an HDD and the like. Therefore various functions are aggregated into one device.
Generally, menus for these functions are displayed in a hierarchical format, and due to the multi-function, the hierarchies of the menus are increasingly deep and complicated. As an example, in the case of a display shown FIG. 18, a user presses respective buttons of an input section such as a remote control and a touch panel, and navigates through the menu hierarchies thereby operating the device. Due to a safety problem such as a problem in which performing such operation during driving leads to distracted steering, the device is configured such that only some of the functions are selectable.
As shown in FIG. 19, most of the functions are each set to notify the user that the function is not selectable when a button thereof is displayed in a toned-down manner, and to be restricted so as not to be executed even if an input thereof is performed. For example, when the user navigates through the menu hierarchies while the vehicle stops at the red light and then the vehicle starts moving after the light turns green, input operation cannot be continuously performed until the vehicle stops next. Further, as a feature of the car navigation device, there may be a case where when the device determines that the vehicle is traveling, the device ends a menu operation screen so as to change the screen to a map screen, and when the vehicle starts moving again, the user may be requested to perform the menu operation from the beginning.
In the case of the conventional input device for the mobile body, when a traveling determination section determines that the vehicle is traveling while the menu hierarchies are navigated through, a history of the previous menu operation may be saved by performing a predetermined operation, and an input to the menu operation may be continued when it is determined that the vehicle travels at a predetermined speed (e.g., see Patent document 1). As another example, there is a device which includes a voice input section which enables an operation of the device even during driving. That is, the user utters a dedicated command which is registered to a dictionary for voice recognition, whereby a function of the device is executed. With this method, the user can safely operate the device without taking their hands off a steering wheel. However, there are hundreds of dedicated commands for the voice recognition, and it is impossible for the user to memorize all the commands. In addition, it is unrealistic for the user to open a user's manual each time so as to find the dedicated command. By displaying a help screen for the voice recognition, the user may be able to recognize some of the dedicated commands. However, the user is not necessarily able to execute a desired function. Further, there is a device in which when the user navigates through the menu hierarchies by using the remote control and the touch panel and finally executes a command, a name of the dedicated command for the voice recognition is informed vocally so as to encourage the use of a voice input (e.g., see Patent document 2).    Patent document 1: Japanese Laid-Open Patent Publication No. 2005-49110    Patent document 1: Japanese Laid-Open Patent Publication No. 2001-216129